Software Defined Radio (SDR) devices are becoming increasingly popular due to their support for mode-, standard- and application-flexibility. At the same time however, the energy consumption of such devices typically suffers from the use of reconfigurable real-time platforms which are known to be severely power hungry. In this work we therefore show how to use tools and techniques developed by the formal methods community to minimize the energy consumption of Finite Impulse Response (FIR) filters which are extensively used in SDR front-ends. We conduct experiments with four different FIR filter structures where we initially derive data flow graphs and precedence graphs using the Synchronous Data Flow (SDF) notation. Based on actual measurements on the Altera Cyclone IV FPGA, we derive power and timing estimates for addition and multiplication, including idling power consumption. We next model the FIR structures in UPPAAL CORA and employ model checking to find energy-optimal solutions in linearly priced timed automata. In conclusion we state that there are significant energy-versus-time differences between the four structures when we experiment with varying numbers of adders and multipliers. Similarly, we find that idle power becomes an important parameter when a high number of functional units are allocated.